Tsumugi is engaged to Yu, heir to a 120-year-old rice-cracker shop, and must win approval from his strict father before marrying into the prestigious family. She appears beautiful, devoted, and pure, but secretly she was the legendary sex worker “Himeka,” ranked number one for two consecutive years. Determined to hide her past, she stresses her chastity and refuses intercourse before marriage. Yet her extensive experience keeps surfacing unconsciously through astonishing sexual techniques, making her fiancé suspicious. His father eventually hires a detective to investigate her background, putting her secret future at risk.